The invention relates to a hose pump, in particular for metering devices in water treatment units, with a pump casing and with a hose for the medium to be pumped that runs through the pump casing in a closed manner, resting on a support wall of the pump casing. In particular, to such an arrangement wherein compression elements are provided for squeezing off the hose in at least two places, and a drive is provided for opening and closing the compression elements in a specific sequence so as to convey a specific volume of liquid through said hose.
Hose pumps are used for metering devices in water treatment units, such as laboratory pumps, for conveying small amounts of a medium to be pumped and also for metering purposes in the medical field. In part, hose pumps are also driven virtually continuously, and thus, are used as pure feed pumps. The medium to be pumped is most often a liquid, for example, water mixed with chemicals in a water treatment unit, a chemical solution, etc.
The known hose pump, from which the invention starts (LUEGER "LEXIKON DER TECHNIK," [Lexicon of Technology] volume 7, "LEXIKON DER ENERGIETECHNIK UND KRAFTMASCHINEN," [Lexicon of Power Technology and Engines], DVA, Stuttgart, 1965, page 264) exhibits a pump casing with a circular interior, whose inner wall presents a support wall for a hose. The hose runs from an intake in a circular loop to an outlet of the pump casing. Concentrically in the pump casing is located the driving shaft of a rotary drive, most often an electric motor, on which a rotating disk sits. On this disk there rest rollers which revolve in planetary fashion and which are pressed by elastic force against the hose made of elastic material, which is wound around the support wall, and press the hose together at regular intervals. As a result, the hose volume located between the two rollers is separated from the suction side and is conveyed to the pressure side. These hose pumps are known to have two, three or even four revolving rollers.
In another design of a hose pump (LUEGER, op. cit.), the pumping effect is achieved by an eccentric rolling piston which shifts in the interior of the pump casing and at the same time presses a ring of elastic material against the support wall. Here, too, the drive is necessarily a rotary drive, therefore most often an electric motor.
The delivery of the known hose pumps must be adjustable, particularly when they are used in metering devices. This necessitates an adjustability of the speed of the driving electric motor. This in turn necessitates relatively expensive control electronics. Overall, the known hose pumps are relatively expensive, on the one hand, because they require an electric motor as a drive, and on the other hand, because they require an electronic speed control.